My nappy bucket smells of Amonia. I've tried a few drops of tea tree oil, and I wash the bucket out between washing- and it still smells. I wash my nappies every 2-3 day x
Have you tried to wash it with soda crystals or bicarbonate of soda and leave it outside to air? I used to do that between washes and it wouldn't smell, would only smell when the nappies went back in there Hope that helps!
I use something from a pet store designed to get rid of wee odours-its a solution which i just put a splash on a peice of kitchen roll and wipe the bucket over. Works amazingly!
I found that some buckets held smells in the plastic, but often a wash with soda crystals did the job. I also out in outside to dry in the sunlight whenever possible.